<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // 父类
        class Person {
            constructor(name, age) {
                this.name = name
                this.age = age
            }

            run() {
                console.log('run...');
            }
        }

        // 子类
        class User extends Person {
            constructor(name, age, sex) {
                super(name, age)
                this.sex = sex
            }

            run() {
                super.run()
                console.log('user run...')
            }

            say() {
                console.log('user say...')
            }
        }

        let u = new User('js', 19, '男')
        u.run()
        u.say()
    </script>
</body>
</html>